The origin and metamorphic history of the ultramafic and metagabbro bodies in the Sanbagawa metamorphic belt.
The origin and metamorphic history of the ultramafic and metagabbro bodies in the Sanbagawa metamorphic belt.
复制标题
三八川变质带超镁铁质和变辉长岩体的起源和变质历史.
DOI：
10.1130/mem164-p375
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发表时间：
1986
期刊：
影响因子：
--
通讯作者：
S. Banno
中科院分区：
文献类型：
--
作者：
K. Kunugiza;A. Takasu;S. Banno
位于四国的三百川变质带的高级区域和Kii半岛含有变质辉长岩、橄榄岩和蛇纹岩。这些岩石仅产于石榴石、钠长石黑云母和斜长石黑云母带中，并且倾向于具有相对于它们所在矿带稳定的平衡矿物组合。不仅可以通过遗迹的矿物学，还可以通过岩石的结构、宏观结构和整体成分来识别前几个平衡阶段的热历史。原岩为层状辉长岩、堆积橄榄岩、残留橄榄岩和石榴石单斜辉石岩。其中一些岩石在侵入三巴川片岩之前为榴辉岩相，另一些为麻粒岩相。在片岩形成的后期，它们被固体侵入体侵位进入变质体制，即侵位是同构造的。部分橄榄岩在三巴川变质作用达到平衡组合之前已形成蛇纹岩，它们的侵位发生在变质作用的早期阶段，而不是沉积阶段。这些奇异地块的源区可能是岛弧的下地壳-上地幔区域。
The higher-grade region of the Sanbagawa metamorphic belt in Shikoku and the Kii peninsula contains metagabbro, peridotite, and serpentinite. These rocks occur exclusively in the garnet, albite-biotite, and oligoclase-biotite zones, and tend to have equilibrium mineral assemblages stable with respect to the mineral zones where they occur. Thermal histories of previous equilibrium stages can be discerned through not only the mineralogy of relics, but also the texture, megascopic structure, and bulk composition of the rocks. The protoliths were layered gabbro, cumulate and residual peridotites, and garnet clinopyroxenite. Some of these rocks were in the eclogite facies before emplacement into the Sanbagawa schists and others were in the granulite facies. They were emplaced into the metamorphic regime by solid intrusion during a later stage of the schistosity formation, that is, emplacement was syntectonic. Some peridotites were serpentinized before attaining equilibrium assemblages of the Sanbagawa metamorphism; their emplacement was during an earlier stage of the metamorphism, but not at the sedimentary stage. The source region of those exotic blocks may have been a lower crust-upper mantle region of an island arc.